drm/amd/display: Read sink freesync support via mccs

drm/amd/display: Read sink freesync support via mccs

If EDID AMD VSDB declares that sink supports MCCS method for freesync
usage, send mccs request to understand sink freesync current supporting
state.

If sink supports freesync but user toggles OSD to turn off it, disable
freesync.

If HDMI sink doesn't support MCCS method for freesync usage, disable
freesync as well.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>